freebsd stuck on Login

In single user mode the file systems are mounted read-only to allow safe inspection and file system checks. If you run UFS please try
mount -a -t ufs
to mount all file systems listed in /etc/fstab to be mounted as specified in that file. In case of zfs the same sequence should be
zfs set readonly=off TheNameOfTheZpool
zfs mount -a
I hope this is helpful.
Bonjour mohamed.s.chebbi,
I have no experience with virtualbox. But usually X should not be started or cannot be started from root, and may be not in single user mode. I hope someone else gets more information out of the log you have uploaded.